Their criticisms mounted when it became clear the date was either in the middle or at the end of the annual October holiday, leading to accusations that thousands of people would miss the vote.

The first minister confirmed on Sunday that the date was "a strong runner" after saying he had all but ruled out staging the referendum in August or September. Until the weekend, he had only said the vote would be held in the autumn of 2014.

Salmond and his officials appeared to backtrack on the date by insisting it was just one under consideration, and stressing that it would only be finalised once the Scottish government's referendum consultation exercise was completed.

Ruth Davidson, the Scottish Tory leader, said this was not good enough. "In Alex Salmond's rush to cosy up to Rupert Murdoch, he has chosen a date which threatens to disenfranchise a huge number of Scots. The SNP's rationale for a Saturday is to boost turnout, but this date would result in the opposite.

"Why does Alex Salmond want to call a poll when many voters are away on holiday? It is simply not acceptable."

The Scottish Labour party said it meant many local government workers would be on holiday, making the staging of the referendum more difficult.

"This raises all kinds of issues like whether there will be sufficient staff to operate polling stations and the overtime costs with very limited research on the impact on turnout," said Patricia Ferguson.